1. Field of the Invention
The present invention relates to a printed wiring board mounting structure, and, in particular, to a printed wiring board mounting structure which is a part of a communication apparatus, an information processing apparatus, or the like, in which structure a plurality of printed wiring boards are mounted on a back panel side-by-side.
2. Description of the Related Art
FIGS. 1A and 1B show a printed wiring board mounting structure 10 in the related art which is incorporated into a shelf (not shown in the figures) of a communication apparatus. The printed wiring board mounting structure 10 includes a back panel 11 having a multilayer wiring structure, and a plurality of printed wiring board units 12. Each unit of the plurality of printed wiring board units 12 includes a printed wiring board 13 on which an LSI circuit 14, and so forth, are mounted. The plurality of printed wiring board units 12 are connected with the back panel 11 through connectors, and mounted on a front surface 11a of the back panel 11 side-by-side, each board unit 12 extending vertically as shown in the figures. The plurality of printed wiring board units 12 are electrically connected by wiring patterns in the back panel 11.
FIGS. 2A and 2B show a printed wiring board mounting structure 20 in the related art, which structure is incorporated into a shelf (not shown in the figures) of an information processing apparatus. The printed wiring board mounting structure 20 is used for performing information processing. The structure 20 includes a back panel 21 which has a multilayer wiring structure. The structure 20 further includes a plurality of front-surface-side printed wiring board units 22 which are mounted on, and connected with, the back panel 21 through connectors on a front surface 21a thereof, side by side, each unit 22 extending vertically as shown in the figures. The structure 20 further includes a plurality of rear-surface-side printed wiring board units 30 which are mounted on, and connected with, the back panel 21 through connectors on a rear surface 21b thereof, side-by-side, each unit 30 extending vertically as shown in the figures. Each of the front-surface-side printed wiring board units 22 includes a printed wiring board 23 on which an LSI circuit 24 is mounted. Each of the rear-surface-side printed wiring board units 30 includes a printed wiring board 31 on which an LSI circuit 32 is mounted. Each of the LSI circuits 24 and 32 includes a driver and a receiver and performs information processing. The plurality of front-surface-side printed wiring board units 22 are connected by wiring patterns provided in the back panel 21. The plurality of rear-surface-side printed wiring board units 30 are connected by wiring patterns provided in the back panel 21. The front-surface-side printed wiring board units 22 are connected with the rear-surface-side printed wiring board units 30 by wiring patterns provided in the back panel 21.
In the printed wiring board mounting structure 20, the drivers of the LSI circuits 24 transmit instructions and the receivers of the LSI circuits 24 receive the instructions, between the plurality of front-surface-side printed wiring board units 22. Further, in the printed wiring board mounting structure 20, the drivers of the LSI circuits 32 transmit instructions and the receivers of the LSI circuits 32 receive the instructions, between the plurality of rear-surface-side printed wiring board units 30. Further, in the printed wiring board mounting structure 20, the drivers of the LSI circuits 24 and 32 transmit instructions and the receivers of the LSI circuits 24 and 32 receive the instructions, between the front-surface-side printed wiring board units 22 and the rear-surface-side printed wiring board units 30.
The printed wiring board mounting structure 10 shown in FIGS. 1A and 1B has the following problems:
Recently, as the processing capacities of the respective printed wiring board units 12 increase, an increase in the number of wiring patterns to be provided in the back panel 11 is needed. In order to increase the number of wiring patterns to be provided in the back panel 11, it is necessary to increase the number of wiring layers of the back panel 11, or to add a jumper wire 15 shown in FIG. 1B. When the number of wiring layers of the back panel 11 is increased, the cost for manufacturing the back panel 11 increases considerably. When the jumper wire 15 is added, the reliability of the back panel 11 is degraded.
The printed wiring board mounting structure 20 shown in FIGS. 2A and 2B has the following problems:
With reference to FIG. 3, transmission of instructions and reception of information between the front-surface-side printed wiring board unit 22-1, the front-surface-side printed wiring board unit 22-2 and the rear-surface-side printed wiring board 30-1 will now be considered. Instructions from the LSI circuit 24-1 of the front-surface-side printed wiring board unit 22-1 pass through a path 40 in the back panel 21 and reach the LSI circuit 24-2 of the front-surface-side printed wiring board unit 22-2. Information from the LSI circuit 24-2 passes through the path 40 and reaches the LSI circuit 24-1. Further, instructions from the LSI circuit 24-1 of the front-surface-side printed wiring board unit 22-1 pass through a path 41 in the back panel 21 and reach the LSI circuit 32-1 of the rear-surface-side printed wiring board unit 30-1. Information from the LSI circuit 32-1 passes through the path 41 and reaches the LSI circuit 24-1. Each of the paths 40 and 41 is long.
The fact that each of the paths 40 and 41 is long is an obstacle to improvement in speed of information processing.
An object of the present invention is to provide a printed wiring board mounting structure which solves the above-described problems.
A printed wiring board mounting structure, according to the present invention, comprises:
a back panel having front-surface-side connectors on the front surface thereof and at least one rear-surface-side connector on the rear surface thereof;
a plurality of front-surface-side printed wiring boards which are mounted on the back panel as a result of connectors provided on the plurality of front-surface-side printed wiring boards being connected with the front-surface-side connectors; and
at least one rear-surface-side printed wiring board which is mounted on the back panel as a result of at least one connector provided on the at least one rear-surface-side printed wiring board being connected with the at least one rear-surface-side connector,
wherein, when seen from the front side of the back panel, the at least one rear-surface-side printed wiring board connected with the at least one rear-surface-side connector crosses the front-surface-side printed wiring boards connected with the front-surface-side connectors.
In this arrangement, the at least one rear-surface-side printed wiring board can act as a part of the back panel. Thereby, it is possible to reduce the number of wiring layers of the back panel. Thus, it is possible to reduce the load borne by the back panel itself. As a result, it is possible to reduce the manufacturing cost. Further, it is not necessary to provide jumper wires, and, thereby, it is possible to improve reliability. Further, when signal processing devices are mounted on the at least one rear-surface-side printed wiring board, the signals are transmitted between the signal processing devices wholly in the at least one rear-surface-side printed wiring board. In this arrangement, in comparison to the related art in which signals are transmitted through the back panel, it is possible to shorten the signal transmission paths, and to improve the signal processing speed.
A server, according to the present invention, is provided with a printed wiring board mounting structure, and the printed wiring board mounting structure comprises:
a back panel having front-surface-side connectors on the front surface thereof and at least one rear-surface-side connector on the rear surface thereof;
a plurality of front-surface-side printed wiring boards which are mounted on the back panel as a result of connectors provided on the plurality of front-surface-side printed wiring boards being connected with the front-surface-side connectors; and
at least one rear-surface-side printed wiring board which is mounted on the back panel as a result of at least one connector provided on the at least one rear-surface-side printed wiring board being connected with the at least one rear-surface-side connector,
wherein:
when seen from the front side of the back panel, the at least one rear-surface-side printed wiring board connected with the at least one rear-surface-side connector crosses the front-surface-side printed wiring boards connected with the front-surface-side connectors; and
the at least one rear-surface-side printed wiring board has a plurality of devices mounted thereon, which devices perform signal processing, and has wiring patterns which connect the plurality of devices and wiring patterns which connect the plurality of devices with the connectors provided on the end of the at least one rear-surface-side printed wiring board.
In this arrangement, because signals transmitted between the devices pass wholly through the at least one rear-surface-side printed wiring board, in comparison to the related art in which the signals pass through the back panel, the signal transmission paths can be shortened. As a result, it is possible to improve the signal processing speed. As a result, it is possible to provide a server in which the signal processing speed is high in comparison to the related art.
A server, according to another aspect of the present invention, is provided with a printed wiring board mounting structure, and the printed wiring board mounting structure comprises:
a back panel having front-surface-side connectors on the front surface thereof and at least one rear-surface-side connector on the rear surface thereof;
a plurality of front-surface-side printed wiring boards which are mounted on the back panel as a result of connectors provided on the plurality of front-surface-side printed wiring boards being connected with the front-surface-side connectors; and
at least one rear-surface-side printed wiring board which is mounted on the back panel as a result of at least one connector provided on the at least rear-surface-side printed wiring board being connected with the at least one rear-surface-side connector,
wherein:
when seen from the front side of the back panel, the at least one rear-surface-side printed wiring board connected with the at least one rear-surface-side connector crosses the front-surface-side printed wiring boards connected with the front-surface-side connectors; and
the back panel has devices mounted thereon in proximity to portions at which the at least one rear-surface-side connector crosses the front-surface-side connectors when seen from the front side of the back panel, the devices performing signal processing.
In this arrangement, it is possible to effectively shorten the signal transmission paths from the front-surface-side printed wiring boards, through the devices, to the at least one rear-surface-side printed wiring board. As a result, it is possible to improve the signal processing speed. As a result it is possible to achieve the server in which the signal processing speed is high in comparison to the related art.
Other objects and further features of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.